@conference {340,
	title = {Binary Relations in Educational Ontologies},
	booktitle = {7th Balcan Conference in Informatics, 2-4 September},
	year = {2015},
	month = {09/2015},
	address = {Craiova, Romania},
	abstract = {<p style="text-align: justify;">The Hellenic Open University{\textquoteright}s mission is to provide distance education at both undergraduate and postgraduate level, developing and implementing appropriate educational materials and teaching methods. For this purpose, educational ontologies are constructed, which are classified into anthologies of Learning Outcomes (LO), Learning Objects (LOb) and Cognitive \&nbsp;Domains (CoD). In contrast to the conceptualization and implementation of LO and LOb ontologies, based on standards available in the literature, the CoD ontologies involve subjectivity derived from the analysis of basic concepts of each CoD and relational expressions that experts use in order to associate these \&nbsp;basic concepts. This subjectivity can create inconsistent ontologies. The aim of this paper is to establish a minimum set of binary relations to be used in the official representation of CoD. These relations are presented by experts with proposals consisting of triples (subject, verb, object) and classified into a Binary Relation (BR) ontology.</p>},
	author = {Lambrini Seremeti and Nikolitsa Aggelopoulou and Christos Pierrakeas and Achilles Kameas}
}
@article {solomou2015characterization,
	title = {Characterization of Educational Resources in e-Learning Systems Using an Educational Metadata Profile},
	journal = {Journal of Educational Technology \& Society},
	volume = {18},
	number = {4},
	year = {2015},
	pages = {246{\textendash}260},
	publisher = {International Forum of Educational Technology \& Society},
	author = {Solomou, Georgia and Christos J. Pierrakeas and Kameas, Achilles}
}
@proceedings {spyropouloudesign,
	title = {DESIGN AND DEVELOPMENT OF A WEB-BASED TOOL FOR SUPPORTING EDUCATORS DURING AN INSTRUCTIONAL DESIGN PROCESS BASED ON LEARNING OBJECTS},
	journal = {7th Αnnual International Conference on Education and New Learning Technologies},
	year = {2015},
	author = {Spyropoulou, Natalia and Christos J. Pierrakeas and Kameas, Achilles}
}
@article {spyropoulou2015developing,
	title = {Developing a Computer Programming MOOC},
	journal = {Procedia Computer Science},
	volume = {65},
	year = {2015},
	pages = {182{\textendash}191},
	publisher = {Elsevier},
	author = {Spyropoulou, Natalia and Demopoulou, Gerasimoula and Christos J. Pierrakeas and Koutsonikos, Ioannis and Kameas, Achilles}
}
@proceedings {16,
	title = {Enhancing self-learning in a Web-Based Course using Predefined Learning Paths},
	journal = {8th annual International Conference of Education, Research and Innovation (ICERI 2015)},
	year = {2015},
	issn = {978-84-608-2657-6},
	author = {Georgia E. Antonelou and Christoforos V. Karachristos and Elias C. Stavropoulos and Vassilios S. Verykios}
}
@proceedings {panopoulouexploiting,
	title = {Exploiting Concept Map Mining Process for e- Content Development},
	journal = {7th annual International Conference on Education and New Learning Technologies},
	year = {2015},
	author = {Panopoulou, Chara and Spyropoulou, Natalia and Christos J. Pierrakeas and Kameas, Achilles}
}
@proceedings {panopoulouextented,
	title = {THE EXTENTED CORRELLATION VERB ONTOLOGY: A NEW APPROACH FOR OBJECT PROPERTIES SPECIFICATION WITHIN DOMAIN KNOWLEDGE REPRESENTATION},
	journal = {11th International Conference Applied Computing},
	year = {2015},
	author = {Panopoulou, Chara and Christos J. Pierrakeas and Kameas, Achilles}
}
@article {solomou2015international,
	title = {International Forum of Educational Technology \& Society},
	journal = {Journal of Educational Technology \& Society},
	volume = {18},
	number = {4},
	year = {2015},
	pages = {246{\textendash}260},
	author = {Solomou, Georgia and Christos J. Pierrakeas and Kameas, Achilles}
}
@inbook {ispoglou2015partial,
	title = {Partial Order Preserving Encryption Search Trees},
	booktitle = {Database and Expert Systems Applications},
	year = {2015},
	pages = {49{\textendash}56},
	publisher = {Springer International Publishing},
	organization = {Springer International Publishing},
	author = {Ispoglou, Kyriakos and Makris, Christos and Stamatiou, Yannis C and Elias C. Stavropoulos and Tsakalidis, Athanasios K and Iosifidis, Vasileios}
}
@article {stavropoulos2015transversal,
	title = {A transversal hypergraph approach for the frequent itemset hiding problem},
	journal = {Knowledge and Information Systems},
	year = {2015},
	pages = {1{\textendash}21},
	publisher = {Springer London},
	author = {Elias C. Stavropoulos and Vassilios S. Verykios and Vasileios Kagklis}
}
@conference {spyropoulou2014clarifying,
	title = {Clarifying the digital content output formats for mobile learning in higher education},
	booktitle = {Interactive Mobile Communication Technologies and Learning (IMCL), 2014 International Conference on},
	year = {2014},
	pages = {139{\textendash}146},
	publisher = {IEEE},
	organization = {IEEE},
	author = {Spyropoulou, Natalia and Karathanasis, Ioannis and Christos J. Pierrakeas and Kameas, Achilles}
}
@article {spyropoulou2014creating,
	title = {CREATING MOOC GUIDELINES BASED ON BEST PRACTICES},
	journal = {EDULEARN14 Proceedings},
	year = {2014},
	pages = {6981{\textendash}6990},
	publisher = {IATED},
	author = {Spyropoulou, Natalia and Christos J. Pierrakeas and Kameas, Achilles}
}
@conference {aggelopoulou2014ontological,
	title = {Ontological Modelling for Intelligent e-Learning},
	year = {2014},
	author = {Aggelopoulou, Niki and Christos J. Pierrakeas and Artikis, Alexander and Kalles, Dimitris}
}
@inbook {makris2014reducing,
	title = {Reducing Redundant Information in Search Results Employing Approximation Algorithms},
	booktitle = {Database and Expert Systems Applications},
	year = {2014},
	pages = {240{\textendash}247},
	publisher = {Springer International Publishing},
	organization = {Springer International Publishing},
	author = {Makris, Christos and Plegas, Yannis and Stamatiou, Yannis C and Elias C. Stavropoulos and Tsakalidis, Athanasios K}
}
@conference {pierrakeas2013correlation,
	title = {A correlation verb (CorrVerb) ontology for object properties specification within knowledge domain representations},
	booktitle = {Proceedings of the 6th Balkan Conference in Informatics},
	year = {2013},
	pages = {195{\textendash}200},
	publisher = {ACM},
	organization = {ACM},
	author = {Christos J. Pierrakeas and Panagiotopoulos, Ioannis and Kameas, Achilles}
}
@conference {nikolopoulos2012creating,
	title = {Creating a LO Metadata Profile for Distance Learning: An Ontological Approach.},
	booktitle = {MTSR},
	year = {2012},
	pages = {37{\textendash}48},
	author = {Nikolopoulos, George and Kalou, Aikaterini K and Christos J. Pierrakeas and Kameas, Achilles}
}
@conference {spanaka2012experience,
	title = {Experience from designing and applying collaborative learning services in distance adult education},
	year = {2012},
	author = {Spanaka, Adamantia and Christos J. Pierrakeas and Kameas, Achilles}
}
@conference {nikolopoulos2012modeling,
	title = {Modeling the characteristics of a learning object for use within e-learning applications},
	booktitle = {Proceedings of the Fifth Balkan Conference in Informatics},
	year = {2012},
	pages = {112{\textendash}117},
	publisher = {ACM},
	organization = {ACM},
	author = {Nikolopoulos, George and Solomou, Georgia and Christos J. Pierrakeas and Kameas, Achilles}
}
@inbook {kouneli2012modeling,
	title = {Modeling the knowledge domain of the java programming language as an ontology},
	booktitle = {Advances in Web-Based Learning-ICWL 2012},
	year = {2012},
	pages = {152{\textendash}159},
	publisher = {Springer},
	organization = {Springer},
	author = {Kouneli, Aggeliki and Solomou, Georgia and Christos J. Pierrakeas and Kameas, Achilles}
}
@inbook {panagiotopoulos2012ontological,
	title = {An Ontological Approach for Domain Knowledge Modeling and Management in E-Learning Systems},
	booktitle = {Artificial Intelligence Applications and Innovations},
	year = {2012},
	pages = {95{\textendash}104},
	publisher = {Springer},
	organization = {Springer},
	author = {Panagiotopoulos, Ioannis and Kalou, Aikaterini and Christos J. Pierrakeas and Kameas, Achilles}
}
@article {pierrakeas2012ontological,
	title = {An Ontological Approach in Learning Programming Languages},
	year = {2012},
	author = {Christos J. Pierrakeas and Solomou, Georgia and Kameas, Achilles}
}
@conference {kalou2012ontology,
	title = {An Ontology Model for Building, Classifying and Using Learning Outcomes},
	booktitle = {Advanced Learning Technologies (ICALT), 2012 IEEE 12th International Conference on},
	year = {2012},
	pages = {61{\textendash}65},
	publisher = {IEEE},
	organization = {IEEE},
	author = {Kalou, Aikaterini and Solomou, Georgia and Christos J. Pierrakeas and Kameas, Achilles}
}
@conference {pierrakeas2012ontology,
	title = {An Ontology-Based Approach in Learning Programming Languages},
	booktitle = {Informatics (PCI), 2012 16th Panhellenic Conference on},
	year = {2012},
	pages = {393{\textendash}398},
	publisher = {IEEE},
	organization = {IEEE},
	author = {Christos J. Pierrakeas and Solomou, Georgia and Kameas, Achilles}
}
@inbook {panagiotopoulos2012ontology,
	title = {An Ontology-Based Model for Student Representation in Intelligent Tutoring Systems for Distance Learning},
	booktitle = {Artificial Intelligence Applications and Innovations},
	year = {2012},
	pages = {296{\textendash}305},
	publisher = {Springer Berlin Heidelberg},
	organization = {Springer Berlin Heidelberg},
	author = {Panagiotopoulos, Ioannis and Kalou, Aikaterini and Christos J. Pierrakeas and Kameas, Achilles}
}
@article {15,
	title = {Impact of cancer patients{\textquoteright} disease awareness on their family members{\textquoteright} health-related quality of life: a cross-sectional survey},
	journal = {Psycho-Oncology},
	volume = {20},
	year = {2011},
	pages = {294{\textendash}301},
	author = {Papadopoulos, A and Vrettos, I and Kamposioras, K and Anagnostopoulos, F and Giannopoulos, G and Pectasides, D and Niakas, D and Economopoulos, T}
}
@article {pierrakeas2009assisting,
	title = {Assisting tutors at the Hellenic Open University in the processes of designing, planning, managing and reusing learning activities},
	journal = {Proceedings of the 2009 European LAMS \& Learning Design Conference},
	year = {2009},
	author = {Christos J. Pierrakeas and Papadakis, Spyros and Xenos, Michalis}
}
@article {theodoratou2009culture,
	title = {Culture specific stress coping strategies used to alleviate occupational stress among Greek nursing personnel},
	journal = {Journal of Medical Psychology},
	volume = {1},
	number = {1},
	year = {2009},
	pages = {21},
	publisher = {Renaissance Medical Publishing},
	author = {Theodoratou, Maria and Andreopoulou, Ourania and Bekos, Vassilis and Christos J. Pierrakeas and Skiadopoulos, Spyros}
}
@article {22,
	title = {4η Ημερίδα Παρουσίασης Δραστηριοτήτων Έρευνας και Ανάπτυξης του Ε.Ε.Υ.Ε.Μ},
	year = {2008},
	author = {Tsakalidis, Athanasios K and Achilles Kameas and Kaporis, Alexis C}
}
@inbook {hadzilacos2008developing,
	title = {On Developing and Communicating User Models for Distance Learning Based on Assignment and Exam Data},
	booktitle = {Intelligent Interactive Systems in Knowledge-Based Environments},
	year = {2008},
	pages = {137{\textendash}155},
	publisher = {Springer},
	organization = {Springer},
	author = {Hadzilacos, Thanasis and Kalles, Dimitris and Christos J. Pierrakeas}
}
@article {kontodimopoulos2008estimate,
	title = {An estimate of lifelong costs and QALYs in renal replacement therapy based on patients{\textquoteright} life expectancy},
	journal = {Health Policy},
	volume = {86},
	number = {1},
	year = {2008},
	pages = {85{\textendash}96},
	publisher = {Elsevier},
	author = {Kontodimopoulos, Nick and Niakas, Dimitris}
}
@article {kalles2008intelligently,
	title = {Intelligently Raising Academic Performance Alerts},
	journal = {1st International Workshop on Combinations of Intelligent Methods and Applications (CIMA), 18th European Conference on Artificial Intelligence, Patras, Greece},
	year = {2008},
	pages = {37{\textendash}42},
	author = {Kalles, Dimitris and Christos J. Pierrakeas and Xenos, Michalis}
}
@conference {pierrakeas2008managing,
	title = {Managing Large Scale Development of Educational Software},
	year = {2008},
	author = {Christos J. Pierrakeas}
}
@article {stamatiou2007cryptographically,
	title = {Cryptographically secured communication between tutors of the Computer Science course of the Hellenic Open University: Experiences from the introductory module {\textquoteleft}Introduction to Computer Science{\textquoteright}(in Greek)},
	journal = {HELLENIC OPEN UNIVERSITY JOURNAL OF INFORMATICS},
	volume = {1},
	number = {1},
	year = {2007},
	author = {Stamatiou, Yiannis and Christos J. Pierrakeas and Xenos, Michalis}
}
@inbook {pierrakeas2007telemedicine,
	title = {Telemedicine applications of speech pathology based on online collaboration environments},
	booktitle = {World Congress on Medical Physics and Biomedical Engineering 2006},
	year = {2007},
	pages = {350{\textendash}353},
	publisher = {Springer},
	organization = {Springer},
	author = {Christos J. Pierrakeas and Georgopoulos, VC and Malandraki, GA}
}
@article {kalles2006analyzing,
	title = {Analyzing student performance in distance learning with genetic algorithms and decision trees},
	journal = {Applied Artificial Intelligence},
	volume = {20},
	number = {8},
	year = {2006},
	pages = {655{\textendash}674},
	publisher = {Taylor \& Francis},
	author = {Kalles, Dimitris and Christos J. Pierrakeas}
}
@inbook {kaporis2006approximating,
	title = {Approximating almost all instances of MAX-CUT within a ratio above the Hastad threshold},
	booktitle = {Algorithms{\textendash}ESA 2006},
	year = {2006},
	pages = {432{\textendash}443},
	publisher = {Springer Berlin Heidelberg},
	organization = {Springer Berlin Heidelberg},
	author = {Kaporis, Alexis C and Kirousis, Lefteris M and Elias C. Stavropoulos}
}
@conference {pierrakeas2006online,
	title = {Online collaboration environments in telemedicine applications of speech therapy},
	booktitle = {Engineering in Medicine and Biology Society, 2005. IEEE-EMBS 2005. 27th Annual International Conference of the},
	year = {2006},
	pages = {2183{\textendash}2186},
	publisher = {IEEE},
	organization = {IEEE},
	author = {Pierrakeas, C and Georgopoulos, VC and Malandraki, GA}
}
@inbook {hadzilacos2006small,
	title = {On small data sets revealing big differences},
	booktitle = {Advances in Artificial Intelligence},
	year = {2006},
	pages = {512{\textendash}515},
	publisher = {Springer},
	organization = {Springer},
	author = {Hadzilacos, Thanasis and Kalles, Dimitris and Christos J. Pierrakeas and Xenos, Michalis}
}
@article {frangides2006snake,
	title = {Snake venom poisoning in Greece. Experiences with 147 cases},
	journal = {European journal of internal medicine},
	volume = {17},
	number = {1},
	year = {2006},
	pages = {24{\textendash}27},
	publisher = {Elsevier},
	author = {Frangides, Christos Y and Koulouras, Vasilios and Kouni, Sophia N and Tzortzatos, Gerasimos V and Nikolaou, Athanasios and Pneumaticos, John and Christos J. Pierrakeas and Niarchos, Constantinos and Kounis, Nicholas G and Koutsojannis, Constantinos M}
}
@inbook {kalles2006using,
	title = {Using genetic algorithms and decision trees for a posteriori analysis and evaluation of tutoring practices based on student failure models},
	booktitle = {Artificial Intelligence Applications and Innovations},
	year = {2006},
	pages = {9{\textendash}18},
	publisher = {Springer},
	organization = {Springer},
	author = {Kalles, Dimitris and Christos J. Pierrakeas}
}
@article {kavvadias2005efficient,
	title = {An efficient algorithm for the transversal hypergraph generation.},
	journal = {J. Graph Algorithms Appl.},
	volume = {9},
	number = {2},
	year = {2005},
	pages = {239{\textendash}264},
	author = {Kavvadias, Dimitris J and Elias C. Stavropoulos}
}
@conference {giannelou2005evaluating,
	title = {Evaluating e-Learning \& Distance Learning Functionality (The Greek Experience)},
	year = {2005},
	author = {Olga Giannelou and Athanasios Styliadis and Christos Pierrakeas}
}
@article {pappa2005validating,
	title = {Validating and norming of the Greek SF-36 Health Survey},
	journal = {Quality of Life Research},
	volume = {14},
	number = {5},
	year = {2005},
	pages = {1433{\textendash}1438},
	publisher = {Kluwer Academic Publishers},
	author = {Pappa, Evelina and Kontodimopoulos, Nick and Niakas, Dimitris}
}
@article {xenos2004assessing,
	title = {Assessing the quality of web sites used in higher open distance education courses},
	journal = {Education, Communication \& Information},
	volume = {4},
	number = {2-3},
	year = {2004},
	pages = {237{\textendash}253},
	publisher = {Taylor \& Francis},
	author = {Xenos, Michalis and Dermitzioti, Evgenia and Christos J. Pierrakeas}
}
@article {pierrakeas2004comparative,
	title = {A comparative study of dropout rates and causes for two different distance education courses},
	journal = {The International Review of Research in Open and Distributed Learning},
	volume = {5},
	number = {2},
	year = {2004},
	author = {Christos J. Pierrakeas and Xeno, Michalis and Panagiotakopoulos, Christos and Vergidis, Dimitris}
}
@inbook {hatzilygeroudis2004pass,
	title = {PASS: An Expert System with Certainty Factors for Predicting Student Success},
	booktitle = {Knowledge-Based Intelligent Information and Engineering Systems},
	year = {2004},
	pages = {292{\textendash}298},
	publisher = {Springer},
	organization = {Springer},
	author = {Hatzilygeroudis, Ioannis and Karatrantou, Anthi and Pierrakeas, C}
}
@article {kotsiantis2004predicting,
	title = {PREDICTING STUDENTS{\textquoteright}PERFORMANCE IN DISTANCE LEARNING USING MACHINE LEARNING TECHNIQUES},
	journal = {Applied Artificial Intelligence},
	volume = {18},
	number = {5},
	year = {2004},
	pages = {411{\textendash}426},
	publisher = {Taylor \& Francis},
	author = {Kotsiantis, S and Christos J. Pierrakeas and Pintelas, P}
}
@booklet {kavvadias2003checking,
	title = {Checking monotone Boolean duality with limited nondeterminism},
	year = {2003},
	publisher = {Citeseer},
	author = {Kavvadias, Dimitris J and Elias C. Stavropoulos}
}
@article {pierrakeas2003evaluating,
	title = {Evaluating and improving educational material and tutoring aspects of distance learning systems},
	journal = {Studies in Educational Evaluation},
	volume = {29},
	number = {4},
	year = {2003},
	pages = {335{\textendash}349},
	publisher = {Pergamon},
	author = {Christos J. Pierrakeas and Xenos, Michalis and Pintelas, Panayiotis}
}
@article {kavvadias2003monotone,
	title = {Monotone boolean dualization is in co-NP [log 2 n]},
	journal = {Information Processing Letters},
	volume = {85},
	number = {1},
	year = {2003},
	pages = {1{\textendash}6},
	publisher = {Elsevier},
	author = {Kavvadias, Dimitris J and Elias C. Stavropoulos}
}
@inbook {kotsiantis2003preventing,
	title = {Preventing student dropout in distance learning using machine learning techniques},
	booktitle = {Knowledge-Based Intelligent Information and Engineering Systems},
	year = {2003},
	pages = {267{\textendash}274},
	publisher = {Springer},
	organization = {Springer},
	author = {Kotsiantis, Sotiris B and Pierrakeas, CJ and Pintelas, Panayiotis E}
}
@article {kotsiantis2002efficiency,
	title = {efficiency of machine learning techniques in predicting students{\textquoteright} performance in distance learning systems},
	journal = {Educational Software Development Laboratory Department of Mathematics, University of Patras, Greece},
	year = {2002},
	author = {Kotsiantis, S and Pierrakeas, C and Pintelas, P}
}
@article {xenos2002survey,
	title = {A survey on student dropout rates and dropout causes concerning the students in the Course of Informatics of the Hellenic Open University},
	journal = {Computers \& Education},
	volume = {39},
	number = {4},
	year = {2002},
	pages = {361{\textendash}377},
	publisher = {Elsevier},
	author = {Xenos, Michalis and Christos J. Pierrakeas and Pintelas, Panagiotis}
}
@article {kaporis2001locating,
	title = {Locating information with uncertainty in fully interconnected networks with applications to World Wide Web information retrieval},
	journal = {The Computer Journal},
	volume = {44},
	number = {4},
	year = {2001},
	pages = {221{\textendash}229},
	author = {Kaporis, Alexis C and Kirousis, Lefteris M and Kranakis, Evangelos and Krizanc, Danny and Stamatiou, Yannis C and Elias C. Stavropoulos}
}
@article {kavvadias2001technical,
	title = {TECHNICAL REPORT No. TR2001/12/03},
	year = {2001},
	institution = {Citeseer},
	author = {Kavvadias, Dimitris J and Elias C. Stavropoulos}
}
@article {kavvadias2000generating,
	title = {Generating all maximal models of a Boolean expression},
	journal = {Information Processing Letters},
	volume = {74},
	number = {3},
	year = {2000},
	pages = {157{\textendash}162},
	publisher = {Elsevier},
	author = {Kavvadias, Dimitris J and Sideri, Martha and Elias C. Stavropoulos}
}
@inbook {kavvadias1999evaluation,
	title = {Evaluation of an algorithm for the transversal hypergraph problem},
	booktitle = {Algorithm Engineering},
	year = {1999},
	pages = {72{\textendash}84},
	publisher = {Springer},
	organization = {Springer},
	author = {Kavvadias, Dimitris J and Elias C. Stavropoulos}
}
@article {skiadopoulos1999phantom,
	title = {A phantom-based evaluation of an exposure equalization technique in mammography.},
	journal = {The British journal of radiology},
	volume = {72},
	number = {862},
	year = {1999},
	pages = {977{\textendash}985},
	publisher = {The British Institute of Radiology},
	author = {Skiadopoulos, S and Pierrakeas, C and Costaridou, L and Kalogeropoulou, CP and Panayiotakis, G}
}
@article {panayiotakis1998evaluation,
	title = {Evaluation of an anatomical filter-based exposure equalization technique in mammography.},
	journal = {The British journal of radiology},
	volume = {71},
	number = {850},
	year = {1998},
	pages = {1049{\textendash}1057},
	publisher = {The British Institute of Radiology},
	author = {Panayiotakis, G and Skiadopoulos, S and Solomou, E and Pierrakeas, C and Costaridou, L and Kalogeropoulou, CP and Dimopoulos, J}
}
@article {kavvadias1998maximal,
	title = {On the maximal models of Horn formulas},
	year = {1998},
	institution = {Citeseer},
	author = {Kavvadias, Dimitris J and Sideri, Martha and Elias C. Stavropoulos}
}
@article {kavvadias1998resolution,
	title = {On a resolution theorem for maximal models},
	year = {1998},
	institution = {Citeseer},
	author = {Kavvadias, Dimitris J and Elias C. Stavropoulos}
}
@article {sotiropoulos1997new,
	title = {A new hybrid genetic algorithm for global optimization},
	journal = {Nonlinear Analysis: Theory, Methods \& Applications},
	volume = {30},
	number = {7},
	year = {1997},
	pages = {4529{\textendash}4538},
	publisher = {Pergamon},
	author = {Sotiropoulos, Dimitris G and Elias C. Stavropoulos and Vrahatis, Michael N}
}
